Bicycle power generator

Abstract

A bicycle power generator includes a tube which is adapted to be installed in a bottom bracket of a bicycle. The tube has a receiving space defined therein. A plurality of coil stators is annularly disposed in an inner periphery of the receiving space. A rotary shaft axially passes through the tube. The rotary shaft has a plurality of magnets annularly disposed on an outer periphery thereof. The plurality of magnets are intervally alternately arranged in north and south polarities. Each end of the rotary shaft has a threaded portion formed thereon for adapting to threadedly connect with a bicycle crank, such that the rotary shaft rotates with the bicycle crank. When the rotary shaft synchronously rotates with the bicycle crank, the plurality of magnets disposed on the rotary shaft is axially rotated relative to the coil stators such that the coil stators generate electricity.

1 . A bicycle power generator comprising:
 a tube adapted to be installed in a bottom bracket of a bicycle, the tube having a receiving space defined therein; a plurality of coil stators annularly disposed in an inner periphery of the receiving space; and   a rotary shaft axially passing through the tube, the rotary shaft having a plurality of magnets annularly disposed on an outer periphery thereof, the plurality of magnets intervally alternately arranged in north and south polarities; each end of the rotary shaft having a threaded portion formed thereon for adapting to threadedly connect with a bicycle crank, such that the rotary shaft rotates with the bicycle crank;   wherein when the rotary shaft synchronously rotates with the bicycle crank, the plurality of magnets disposed on the rotary shaft is axially rotated relative to the coil stators such that the coil stators generate electricity.   
     
     
         2 . The bicycle power generator as claimed in  claim 1 , further comprising two caps respectively connected to two ends of the tube; each cap having a penetrating hole defined therein, the threaded portions of the rotary shaft respectively passing through the penetrating holes; each cap having a connecting portion formed on one end thereof for adapting to connect with the bottom bracket; wherein the caps are partially received in the bottom bracket and the tube is securely installed therein. 
     
     
         3 . The bicycle power generator as claimed in  claim 2 , wherein each cap includes a bearing disposed in an inner periphery thereof for holding the rotary shaft; the rotary shaft axially passing through the tube via the bearings, such that the plurality of magnets disposed on the rotary shaft are inserted into the tube;
 wherein when the rotary shaft is rotated, the bearings stably hold the rotary shaft, the rotary shaft axially disposed in the receiving space, the rotary shaft being interspaced relative to the coil stators, such that the plurality of magnets do not collide with the coil stators during rotation.   
     
     
         4 . The bicycle power generator as claimed in  claim 2 , wherein each connecting portion has a plurality of threads annularly formed on an outer periphery thereof, such that the connecting portions are provided for threadedly connecting with the bottom bracket of the bicycle. 
     
     
         5 . The bicycle power generator as claimed in  claim 1 , further comprising an electricity storage device electrically connected to the coil stators.